In-situ OAM IPv6 Options

In-situ Operations, Administration, and Maintenance (IOAM) records operational and telemetry information in the packet while the packet traverses a path between two points in the network. This document outlines how IOAM data fields are encapsulated in the IPv6 .

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

Abbreviations used in this document: Edge-to-Edge In-situ Operations, Administration, and Maintenance Operations, Administration, and Maintenance Proof of Transit

In-situ OAM in IPv6 is used to enhance diagnostics of IPv6 networks. It complements other mechanisms proposed to enhance diagnostics of IPv6 networks, such as the IPv6 Performance and Diagnostic Metrics Destination Option described in . IOAM data fields are encapsulated in “option data” fields of two types of extension headers in IPv6 packets - either Hop-by-Hop Options header or Destination options header. The selection of a particular extension header type depends on IOAM usage, as described in section 4 of . Multiple options with the same Option Type MAY appear in the same Hop-by-Hop Options or Destination Options header, with varying content. In order for IOAM to work in IPv6 networks, IOAM MUST be explicitly enabled per interface on every node within the IOAM domain. Unless a particular interface is explicitly enabled (i.e. explicitly configured) for IOAM, a router MUST drop packets which contain extension headers carrying IOAM data-fields. This is the default behavior and is independent of whether the Hop-by-Hop options or Destination options are used to encode the IOAM data. This ensures that IOAM data does not unintentionally get forwarded outside the IOAM domain. An IPv6 packet carrying IOAM data in an Extension header can have other extension headers, compliant with . IPv6 Hop-by-Hop and Destination Option format for carrying in-situ OAM data fields:

8-bit identifier of the type of option. 8-bit unsigned integer. Length of the Reserved and Option Data field of this option, in octets. 8-bit field MUST be set to zero upon transmission and ignored upon reception. 8-bit field as defined in section 7.2 in . Variable-length field. Option-Type-specific data. In-situ OAM Options are inserted as Option data as follows: Pre-allocated Tracing Option: The in-situ OAM Preallocated Tracing option defined in is represented as a IPv6 option in hop by hop extension header: 001xxxxx 8-bit identifier of the IOAM type of option. xxxxx=TBD. IOAM Pre-allocated Trace Option Type. Incremental Tracing Option: The in-situ OAM Incremental Tracing option defined in is represented as a IPv6 option in hop by hop extension header: 001xxxxx 8-bit identifier of the IOAM type of option. xxxxx=TBD. IOAM Incremental Trace Option Type. Proof of Transit Option: The in-situ OAM POT option defined in is represented as a IPv6 option in hop by hop extension header: 001xxxxx 8-bit identifier of the IOAM type of option. xxxxx=TBD. IOAM POT Option Type. Edge to Edge Option: The in-situ OAM E2E option defined in is represented as a IPv6 option in IPv6 option in destination options extension header: 000xxxxx 8-bit identifier of the IOAM type of option. xxxxx=TBD. IOAM E2E Option Type. All the in-situ OAM IPv6 options defined here have alignment requirements. Specifically, they all require 4n alignment. This ensures that 4 octet fields specified in such as transit delay are aligned at a multiple-of-4 offset from the start of the Hop-by-Hop Options header. In addition, to maintain IPv6 extension header 8-octet alignment and avoid the need to add or remove padding at every hop, the Trace-Type for Incremental Tracing Option in IPv6 MUST be selected such that the IOAM node data length is a multiple of 8-octets.

This document describes the encapsulation of IOAM data fields in IPv6. Security considerations of the specific IOAM data fields for each case (i.e., Trace, Proof of Transit, and E2E) are described in defined in . As this document describes new options for IPv6 , these are similar to the security considerations of and the new weakness documented in .

This draft requests the following IPv6 Option Type assignments from the Destination Options and Hop-by-Hop Options sub-registry of Internet Protocol Version 6 (IPv6) Parameters. http://www.iana.org/assignments/ipv6-parameters/ipv6- parameters.xhtml#ipv6-parameters-2

The authors would like to thank Tom Herbert, Eric Vyncke, Nalini Elkins, Srihari Raghavan, Ranganathan T S, Karthik Babu Harichandra Babu, Akshaya Nadahalli, Stefano Previdi, Hemant Singh, Erik Nordmark, LJ Wobker, Mark Smith, and Andrew Yourtchenko for the comments and advice. For the IPv6 encapsulation, this document leverages concepts described in . The authors would like to acknowledge the work done by the author Hiroshi Kitamura and people involved in writing it.